Field of the Invention
The invention relates to an optical mechanism, and more particularly to an optical mechanism including a glass-made bracket joining polarization beam splitters and panels.
Description of the Related Art
Referring to FIGS. 1 and 2, an optical mechanism for a conventional silicon based liquid crystal pico projector is shown. The optical mechanism includes two silicon-based liquid crystal panels 10, two polarization beam split plates 20, two polarization beam split cubes 30, a plastic housing 40 and two lenses 50. The silicon-based liquid crystal panels 10, the polarization beam split plates 20 and the polarization beam split cubes 30 are disposed in the plastic housing 40. The lenses 50 are disposed near the polarization beam split cubes 30. The plastic housing 10 has a thermal expansion coefficient different from those of the polarization beam split plates 20 and the polarization beam split cubes 30. In addition, accuracy of the plastic housing 40 depends on the injection molding process and assembly process. Therefore, the optical mechanism is liable to variations in dimensions and assembly, which cause poor contrast and sharpness of the projector.
Pico projectors which are applicable to the wearable devices have become the mainstream as wearable devices become popular. At present, a wearable device must be equipped with two pico projectors for a person's two eyes. Therefore, the optical axes of the two pico projector must have high related accuracy and stability. However, the conventional pico projectors as shown in FIGS. 1 and 2 are mounted individually, which may cause the following problems:
the optical axes of two pico projectors have variations caused by temperature elevation;
the optical axes of two pico projectors become non-parallel due to imprecise assembly; and
images generated by the two pico projectors cannot be completely overlapped due to pixel deviation of the panels.